This invention relates to a flowcell which may be generally defined as a device used in spectrophotometry, transparent to an energy source, carrying a solution stream, and placed in a path between a monochromatic light source and detection system for the purpose of measuring changes in the optical absorbance or light transmissivity of the solution stream.
Flowcells are commonly used in fluid analyzers having spectrophotometers or colorimeters. A colorimeter or spectrophotometer is a device for measuring the optical density or light transmissivity of fluids, solutions, or gases; either in stasis or in dynamic flow. Light at selected wavelength, over the visible and/or ultra-violet wavelengths, passes through a flowcell. In particular, the light passes through a solution, or fluid, flow passage of the, flowcell carrying the fluid, or solution, being analyzed. The sample being analyzed modulates, or attenuates, the input light so as to yield a light output from the flowcell which is representative of a particular characteristic of the fluid, or solution, being analyzed. The light output is detected and electrically processed to provide an electrical signal which in turn provides intelligible information representative of the particular characteristic of the fluid, or solution.
In some analyzers a multitude of analyses may be made on a time-shared basis and therefore it is common to employ large numbers of flowcells each of which receives an input light and provides a corresponding light output representative of the particular characteristic being analyzed.
Previous flowcells comprise transparent bodies disposed at various locations within the analyzer to which fluid carrying conduits are connected. Each flowcell comprises a fluid inlet and a fluid outlet which may take the form of nipple-like fittings. Specifically, such nipple-like fittings comprise circular tubes axially spaced apart and projecting radially of the main cylindrical body of the flowcell. The path of fluid through a flowcell is radially inwardly through one fitting into a radial bore within the flowcell body, then axially along a central axial bore within the body to another radial bore which carries the fluid radially outwardly to exit through the other fitting. The fluid carrying conduits, or lines, to and from the flowcell are typically flexible hoses fitted over the ends of the nipple-like fittings. The inlet and outlet fittings of prior flowcells are circumferentially aligned, being lodged into circumferentially aligned radial bores in a unitary portion of the flowcell body. It has also heretofore been the practice to fixedly mount the body of the flowcell on a suitable holder which is in turn used to mount the flowcell within the analyzer.
In the prior flowcells light from a suitable source is supplied to one axial end of the flowcell body. The light is conducted to the flowcell by a suitable medium, such as an optical fiber, so as to enter one end of the central axial bore through the flowcell body. The light thereafter passes through the fluid as it flows axially through the flowcell, and having been attenuated or modulated by the particular characteristic of the fluid being analyzed, the light exits via the opposite axial end of the flowcell body. The exiting light is conducted away via an optical fiber at the opposite axial end of the flowcell body to additional components of the colorimeter for processing to ultimately develop the intelligible information representative of the particular characteristic of the fluid which is being analyzed by this particular flowcell.
An analyzer contains various other components in addition to flowcells. As such, these are usually contained within a console, or housing, and the flowcells are distributed throughout the housing in various locations, or in banks. With the prior flowcells, certain of these locations are often inaccessible for making connections with the flowcells. Hence, if a flowcell needs to be removed and replaced, it is often a difficult task to perform the removal and replacement because of the presence of additional components in the vicinity and close quarters.
Moreover, the construction of the prior flowcells necessitated replacement of a clogged flowcell by a new one. In other words, cleaning of a clogged flowcell was impractical, and the clogged flowcell was scrapped. Prior flowcells are beset by further problems; one such flowcell is an extremely delicate unit subject to easy breakage due both to: (a) inherently fragile material (glass) and (b) joining of materials traditionally incompatible (glass and metal). In use, any damage to the flowcell is typically catastrophic. If dropped, it is destroyed instantly: if there is a slight misalignment of the fiber optic calipers, the metal light masks are stressed and will soon break away from the body or the body will separate from the metal mount. If great care is not exercised in making connections to its glass entry/exit ports, they are easily snapped off. Optical quality is not uniform, varying by up to 30% in transmitted light from unit to unit.
The present invention is directed to a new and improved flowcell which possesses important advantages and benefits over prior flowcells of the type described above.
One important advantage of the present invention is that the flowcell can be quickly disassembled into two halves for convenient cleaning and unclogging when needed. Hence, it is unnecessary for a clogged flowcell to be discarded and replaced by a new one. This can yield a savings to the user of flowcells.
Another important advantage of the invention is that the construction of the flowcell provides for more convenient installation, and replacement, particularly in regard to connection of lines to the flowcell. In this regard the flowcell is endowed with a capability whereby the inlet and outlet ports may be relatively positioned with respect to the axis of the flowcell body independently of each other and the flowcell body itself may be independently adjusted relative to its holder. Thus, in an installation where it may be difficult or indeed impossible to make connections to a prior type of flowcell, a flowcell embodying principles of the present invention can be easily adjusted so that its connections and mounting can be more expeditiously and easily accomplished.
Briefly, the flowcell of this invention comprises an interposed fluid pathway, coaxial with the light path of a fiber optic system and consisting of two or more units combined by means of interference-fit joints which both accurately align the bores and seal against leakage. The joints are so fashioned that the flowcell may be quickly disassembled to permit cleaning or removal of lint fibers, crystals or other minute materials which typically deposit and obstruct both solution flow and light transmission. At each end of the fluid pathway, a short rod of a clear material of broad spectral transmissivity such as quartz, fused silica, sapphire, etc., acts as a fluid seal and window to the fluid pathway. Fluid enters and exits the pathway by means of ports located at right angles to the light path.
The foregoing features, advantages, and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a preferred embodiment of the invention according to the best mode contemplated at the present time in carrying out the invention.